


Masquerade

by SprucePines



Category: Gravity Falls
Genre: Brother-Sister Relationships, F/M, Sibling Incest, Siblings, Twincest
Language: English
Status: Completed
Published: 2015-08-18
Updated: 2015-08-18
Packaged: 2018-04-15 10:26:18
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 3,260
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/4603299
Author URL: https://archiveofourown.org/users/SprucePines/pseuds/SprucePines
Summary: <blockquote class="userstuff">
              <p>Dipper and Mabel each receive invitations to a masquerade dance and unknowingly meet up.</p>
            </blockquote>





	Masquerade

Mabel had first heard rumors about it about a month before. She had been washing her hands in the restroom when she overheard a few other girls talking about it as they entered. A masquerade dance, being held by one of the richest families in town. Personal invitation only. Only the well to do and well connected would be seen there.

While the other girls were lamenting their lot in life, being mere college freshmen without the connections to make such a dream a reality, Mabel was already withdrawing her cell phone from her purse and dialing Northwest Mansion in Gravity Falls. One brief conversation with Pacifica later and Mabel soon received an email inviting her to the social event of the century.

She immediately began work on her dress. She had every intention of getting noticed at this dance, and her dress was going to make that happen. A person with as bright and shiny a personality as hers could only go to the ball as one thing.

She would be the sun.

Mabel bought up nearly all the yellow and gold fabric she could get her hands on and spent hours at her sewing machine, stitching up hems and pleats, adding bunting. She lost track of how many time she accidentally stuck herself with her sewing needle. But when she was finished, she was certain that she would be the brightest thing on the dance floor.

There was only one important thing missing: a mask. Some modeling clay later and she had a mask that covered nearly her entire face apart from her mouth and chin. She even added some sunbeams radiating out from her face. Painted gold, it complemented her dress perfectly.

Looking at her reflection in the mirror, Mabel couldn’t recognize herself. Without one of her ever present sweaters, she saw that she had grown quite curvaceous. She was concerned at first about showing too much cleavage, but now that she could see herself in it, she found herself wondering about showing off more.

“Better not press your luck, Mabel,” she told herself. “There’s sexy and then there’s scandalous.”

The night of the party, she was surprised to find a limo waiting outside her dorm for her. She recognized the driver as one of Pacifica’s, and he handed her a note which read, “There’s no way a friend of mine is going to a party like this in a plain Jane car. Knock ‘em dead.” Inside, she found that the minibar was fully stocked. Unable to resist, and after checking to see if the driver was watching her, she mixed up a mimosa and quickly downed it. She quickly followed it with two more before she felt the limo come to a stop.

When the chauffeur opened the door, Mabel stepped out in front of the ritziest hotel in town. A smattering of incoming guests lined up at the door. Even the hotel staff was taking part in the festivities in their own small way, sporting domino style masks.

The concierge gave her a reproachful look, but that quickly disappeared the instant he saw that she was there courtesy of the Northwest family. Giving him a smug look of her own, Mabel entered the main ballroom.

A slow jazz tune was playing over the PA system as various couples danced. She stood and watched as the song ended and a foxtrot began. Without missing a beat, everyone on the floor picked up the tempo and continued to dance.

Spotting the punch bowl, Mabel carefully navigated her way around the perimeter of the room. She picked up a cup and took a sip just as the music died away again. There was a moment of silence before the walls began to shake from the _unntss unntss unntss_ of a modern dance track.

Again, the dancing bodies adapted to the change, hips gyrating and feet stomping. Mabel noticed that some of the pairs had drifted together forming small dancing clusters. As she gazed at one such group, she began to feel as though someone was watching her. Scanning around the room, her eyes fell on someone on the far side of the room looking directly at her. Like everyone, his face was mostly obscured, but the mask he was wearing caught her attention.

It was of a pale, blue moon.

Mabel felt her heart skip a tiny beat. When she saw the mystery man begin to cross the floor towards her, she had to remind herself to breathe.

*********

Dipper received the invitation completely out of the blue. He woke one morning to find it sitting in his email inbox. Along with it was another email, this one from a friend:

_Dipper,_

_You’ve spent every night this semester shut up in your dorm. You need to get out, have some fun, maybe even meet somebody. I got you an invitation to the privatest of private parties in two weeks. Do NOT let it go to waste. Rent yourself a tux and send the bill to me. I got you covered. And if you should happen to hook up with anyone (wink,wink), get yourselves a room there, too._

_And for god’s sake, have some fun!_

_R.F._

Dipper shook his head. Of course his friend, Reg, would do something like this. He’d been trying to coax Dipper out of his self-imposed shell since they met in class. He had helped Reg recover his grades from a bad midterm and he’d been wanting to repay the favor ever since.

He skimmed through the details on the invitation. An extremely private party, at one of the top five-star hotels in town, it was certainly a far cry from the shindigs he was used to. In fact, the last upscale party he’d attended was at the Northwest Mansion in Gravity Falls years ago. Dipper considered for a moment before deciding that, yes, he did deserve to take a little break for once.

Renting the tuxedo was easy enough, but as he stood at the counter, he was at a loss for what to do about a mask. His answer came when his eyes fell on a display of cufflinks. One set in particular caught his eye. They resembled the surface of the moon. On the spur of the moment, he bought the links out of his own pocket and picked up a simple cloth mask and some paint on the way back to his dorm.

Though he lacked his twin sister’s craftsmanship, he managed to not bungle things up. As a matter of fact, he though he didn’t do a half bad job. Looking at himself in the mirror was almost like looking at a stranger.

When the taxi deposited him outside the hotel, he couldn’t quite believe his eyes. Tuxes, fancy dresses, and masks were all around him. Every face, even the staff’s, were obscured by masks. He presented his invitation to the concierge, who politely welcomed him.

He crossed the threshold of the ballroom just as a foxtrot ended, soon followed by the jarring thump of heavy bass. He skimmed his eyes over the gathered revelers, seeing numerous couples, but also a number of trios and even a foursome or two, grinding their bodies together as they swayed to the beat.

As he looked at a pair of gentlemen dancing together (or at least, he assumed so based on the tuxedos), a bright flash of yellow caught his attention. Shifting his focus, he saw a brilliant yellow and gold dress. As its wearer turned his way and their eyes met, his breath paused.

She was wearing a mask of the sun.

Before he knew what he was doing, his legs were carrying him across the dance floor.

*********

“H-hi,” he said when he reached her.

“Hi,” she said meekly. There was something in the tone of his voice that seemed familiar, though she couldn’t quite place it with the noise.

“Are you here with anyone?” he asked. She shook her head no. “How can that be?”

“What do you mean?” she asked.

“A lady wearing such a beautiful dress must have the pick of all the guys. Or girls.”

“I-“ she began, “I’m only here be because a friend got me invited.”

He gaped at her. “You, too? So am I.”

“So…” she said, a hint of hopefulness in her voice, “you’re not here with anyone either?”

He shook his head, causing her grin to grow a bit wider.

“You really think my dress is beautiful?”

“I do,” he said, returning her grin.

“Thank you. I actually made it myself.”

“You’re kidding. It looks professional!”

“Oh, go on.”

“No, really! I haven’t seen a handmade dress done this well since my sister.”

“Is she that good?” she asked.

“At least,” he answered. “She’s always been great at creating things. It’s her gift.”

The thumping bass gradually died away and a waltz began. He held his hand out to her.

“May I have this dance?”

He couldn’t help but grin as she giggled her agreement and took his hand. He guided her out amongst the other dancers and gently places his hand on her waist as they begin to twirl away.

She looked into his eyes, again getting a sense of something familiar about him. She wished she could figure it out. Suddenly, he began to chuckle. “What’s so funny?” she asked.

“I just realized that you’re the sun, and I’m the moon, and we’re spinning around almost like we’re day and night trying to catch each other.”

She thought about it for a moment and smiled. “It must be fate.”

He smiled back. “Maybe.”

The waltz came to a close and another thumping dance tune took its place. Letting the rhythm carry her, she began to sway her hips to the beat. He let go of her hand and placed it on her other hip while hers reached up to his shoulders. He followed her lead, trying to move his hips like she was, though it wasn’t easy.

Suddenly, she spun around to face away from him, pressing up against his pelvis with her bottom. He started to feel the blood rush down below, especially when her hand reached behind them both and cupped his butt. He looked at her as she tilted her head back and gave him a sultry stare.

He couldn’t quite believe it. No one had ever really made him feel this way before, even his preteen crushes. His hands began to caress her sides, his fingertips barely brushing past the sides of her breasts. She shuddered, which only further spurred him on. Unable to resist, he leaned down and sinks his lips onto the bare skin of her neck. She gasped in both surprise and arousal.

After suckling at her for several seconds, he brought his lips up close to her ear. “Would you like to take this elsewhere?”

She took a moment to catch her breath. With a husky voice, she answered, “Yes.”

*********

As they rode up alone in the elevator, they repeatedly stole glances at each other. More than once, he stared at her cleavage. He found himself licking his lips, eager to see them set free. Suddenly, she surprised the both of them by reaching over onto his groin, feeling his growing erection through his pants.

When the door to their room opened, the two of them nearly tumbled inside, their lips locked and their hands exploring each other. Awkwardly, they approached the bed. He reached to remove her mask, but she stopped him.

“No, let’s leave them on,” she said with a grin.

He nodded. “Okay.” She reached for his bowtie and tugged it loose while he reached around her and began to unzip her dress. In moments, their clothes were carefully laid out over the chairs, leaving them in their underwear.

He made the first move, taking hold of her breasts through her bra and burying his face between their softness. She closed her eyes and drew in a sharp breath before she reached down between his legs and into the fly of his boxers. She gripped his cock, giving it a few slow strokes.

He unhooked her bra, letting it fall to the floor before sucking a nipple into his mouth. He flicked his tongue over it repeatedly, drawing tiny gasps from his date. Finally, she pried his mouth away long enough to look into his eyes and latch her lips onto his, her tongue forcing its way into his mouth.

As they kissed, they collapsed onto the bed, his hand continuing to knead her breast while her hand kept a grip on his penis. Slowly, he pulled away and crawled backwards, peppering her skin with kisses until his head was hovering over her crotch. With a grin, he slowly peeled off her panties and gently spread her thighs, exposing her pussy. After a final glance up into her eyes, he leaned down and danced his tongue over her clit.

Her eyes clamped shut and her back arched as a finger gently penetrated her, probing her insides. He continued to lick and suck for a moment before realizing that his mask was beginning to get in the way. With his free hand, he quickly pulled his mask off without pausing. An instant later, her hand snaked down and tangled itself into his hair.

As she felt her orgasm approach, she began to roll her hips, grinding herself onto his mouth. Her breath began to quicken and she looked down, wanting to look into her lover’s eyes as she came.

What she saw instead was her brother’s birthmark.

Unable to stop it, she screamed as her orgasm washed over her, just as much from pleasure as from shock. She laid back, trying to rationalize what had just happened as Dipper crawled back up to face her. The sight of her brother licking his lips as he looked down at her with a satisfied gleam in his eye only served to drive home what they’d just done.

When he saw the fear and dread in her eyes, his expression instantly softened. “What’s wrong?” he asked.

Unable to speak, she rolled off the bed, hands covering herself back up.

“What is it?” he asked, more urgently. “What did I do?”

She averted his gaze, scrambling for her bra and panties. As she reached, his hand gently grasped her arm and brought her up to look at his face. Dipper looked into her eyes, seeing them nearly in tears. “Please,” he said, “what is it?”

Finally, managed to speak a single word: “Dipper.”

Dipper looked at her in shock. He reached up and pulled away her mask, revealing a teary-eyed Mabel. He quickly stumbled backward, hands gripping the dresser. “Oh, shit,” he whispered.

“I didn’t know it was you,” Mabel said.

“Ho-how did you get in?”

“Pacifica. What about you?”

“Reggie Fairbanks.”

Mabel put her face into her hands. “Oh, god…we danced…”

“And then you pressed up against me…”

“And you got turned on…”

“And then I brought you up here…”

“And then you…” She didn’t finish. They both knew exactly what he’d done next.

“Oh, god, I’m so sorry, Mabel. If only I’d known you were going to be here, too.”

Mabel shook her head. “I’m sorry, too. I was having such a good time.”

“So was I.”

“You were such a good dancer.”

“Really?” He couldn’t help but grin a bit at the compliment. “You, too.”

“And…” Mabel began to blush. “A really good kisser.”

Dipper reddened a bit, too. “Y-you, too.”

“And just now…Where did you even learn to do that?”

He began to rub the back of his neck. “Um…internet porn.”

“I just…” Mabel shook her head in disbelief. “I know this is wrong and all, but…that was…amazing.”

Dipper looked at his sister. “It was?”

“I never felt anything so good before.”

He grinned a little bit. “Um, thanks…I guess.”

“I…I’m almost sorry we have to stop.”

Dipper stared at her. “What?”

“I don’t know, but…it felt so good up until I saw that it was you…I guess a little part of me doesn’t want to stop.” Mabel looked at her twin hesitantly. “Do you?”

He gazed at his sister, still nude. He felt his lower regions still stirring at the sight. He took a breath. “Are you sure?”

Mabel thought a moment before answering. “Kiss me and let’s find out.”

Dipper swallowed and slowly stepped towards Mabel. His heart pounding, he leaned in and placed his lips over hers. A moment later, she responded by kissing him back. Almost at once, the fear they were feeling began to fall away. Yes, this was wrong, but they both wanted it to happen.

Mabel tugged at Dipper’s undershirt and he broke their kiss long enough for her to pull it over him while he pushed his boxers to the floor and stepped out of them. Her hand once again wrapped itself around his shaft and slowly stroked him to full hardness.

Once he was ready, he stepped back to his tuxedo and pulled out his wallet. From inside, he took out a condom. Mabel rubbed herself as she watched her brother roll the rubber onto himself and laid back as he climbed over her, stopping with his cock a hair’s breadth away from entering her. He looked into her eyes one last time, looking for her confirmation. She silently nodded her head and he carefully pressed forward, plunging himself into his twin.

She cried out slightly as she felt herself being filled. Her muscles instinctively flexed around Dipper. Even through the latex, the sensations made him gasp. He slowly withdrew from her before thrusting back in, causing his sister to gasp in time. After a moment, she grasped his cheeks and looked deep into his eyes. “Dipper,” she moaned, “deeper.”

Hearing his sister’s voice sounding so desperate sparked something deep inside him, something almost primal. He sped up his pace and pushed forward harder with each thrust, lifting her legs over his shoulders, desperate to sink deeper into her.

Mabel looked up at her twin and pulled his face down to hers for a kiss. With one final thrust, he gasped into his sister’s mouth as he came. She kept their faces clamped tight together as he rode the crest. Gradually, the wave subsided and Dipper came back down, his deflating member slipping out of her. He removed the spent condom and tied it shut before dropping it into the wastebasket and laying down next to Mabel. They spent the next several seconds looking into each other’s eyes.

“Well,” he finally said, “we just did that, didn’t we?”

“We did.” She paused, not sure if she should ask her question. “Did you…enjoy it?”

Dipper gave his sister a tiny smile and nodded his head. “Why? Didn’t you?”

Mabel wrapped her arms behind his neck. “I did, but I’m afraid we may have royally borked our relationship.”

“Mabel, you’re my twin sister. Nothing will ever change that.”

“But where do we go from here?”

He leaned forward and pressed his forehead to hers. “Mabel, if you want us to never speak of this again, then my lips will be forever sealed.”

There was another moment of silence before she asked her next question.

“And if I want this to continue?”

Dipper grinned at her. “Then just say the word.”

She returned his grin and gave him a kiss. “We have this room all night, don’t we? Let’s make the most of it.”


End file.
